GM Muscle Car Handling and Performance Upgrades

In this chapter I discuss several specific types of GM muscle cars and go over some strong and weak points of each design. I also cover some aftermarket parts and how they work in various applications. Each section builds upon the last, so read all of the sections even if you don’t have one of those cars. You may accidentally learn something cool!

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GM A-Body

Probably the most produced of all the muscle cars, the GM A-bodies were made by every GM brand except Cadillac and GMC. They were good sellers too. Pontiac’s LeMans/Tempest/GTO, Chevrolet’s Chevelle/Malibu/Super Sport, Buick’s Skylark/Gran Sport (GS), and Oldsmobile’s Cutlass/442 are still surprisingly plentiful. Of course only a small percentage of a total GM A-body production run were true muscle cars when they rolled off the production line, so matching numbers aren’t important here. As far as I’m concerned, a Chevelle that started off with a 307 and Powerglide but now runs modern suspension, brakes, 5-speed manual transmission, and 600 hp is much more of a muscle car than a 325-hp 396-ci Chevelle SS ever was! Heck, in my opinion, a four-door station wagon with those performance mods is a muscle car too (and they are out there).

These cars are split into four generations: the first from 1964 to 1967, the second from 1968 to 1972, the third from 1973 to 1977, and the fourth from 1978 to 1980. This last generation is kind of the black sheep of the A-body clan; in 1981 they were reclassified as G-bodies and continued under that moniker until 1988.

GM A-body muscle cars are abundant and come in a wide variety of shapes and sizes. They all share the same common flaws, but they can be vastly improved with the application of re-engineering and proper selection of aftermarket parts. Done properly, they can be amazing performance cars. (Photo Courtesy RideTech)

The GM family tree has many branches. The 1973 to 1977 A-bodies used the front suspension from the 1970 to 1981 F-bodies, which later went on to be used on the 1978 to 1996 GM B-bodies, which included the Chevy Impala/Caprice, Buick Roadmaster, and others you may not expect (like two-wheel-drive Chevy Astro vans). The rear suspension of those cars was basically 1973 to 1977 A-body as well. The G-body front end was used for the two-wheel-drive S-10 pickups and was still manufactured until 2005 with very few changes.

The geometry of the 1964 to 1972 models is almost identical, and basically very bad. The 1973 to 1977 models are not bad. The 1978 to 1980 (and by extension, the 1981 to 1988 G-body) are actually slightly worse than the 1964 to 1972 A-bodies. The only reason they generally drive a little better is the improved tuning (sway bars, spring rates, shocks, and tire technology).

GM A-Body 1964 to 1972

With the 1964 to 1972 A-bodies, the first concern is their front end and steering geometry. It’s just plain lousy. It’s actually backward in pretty much every way that it can be. They have pronounced positive camber gain in bump, a subterranean roll center that’s very unstable, and a healthy dose of bump steer. As far as I’m concerned, doing anything to this chassis without fixing these issues is like putting lipstick on a pig.

To correct these issues, you need to target the problem areas and tweak them into shape. Because they’re geometry problems, you need to move the suspension’s pickup points to get the job done. In this case, the pickup points of the upper ball joints need to go up, a lot. Raise them until they’re traveling in an inward arc as soon as the suspension starts to compress. That helps give you proper negative camber gain. The most popular ways to do this are by adding taller spindles or taller ball joints.

Tall Spindle Swaps: Tall spindle swaps date back to the 1980s, with outfits like HO Racing using B-body spindles with B-body lower ball joints that were machined down to fit the A-body’s lower A-arms. Second-generation (1970 to 1981) GM F-body spindles and ball joints also work. Getting a decent alignment out of these early packages was always a real challenge (even with offset cross shafts) and in some cases it was impossible. The additional height and more-aggressive ball-joint axis inclination made the stock upper A-arms poorly suited for use with these spindles. Even on a good day, alignment options were severely limited. The situation improved when companies started making application-specific tubular upper A-arms (for this swap) that were shorter, and had more offset toward the firewall. These helped make it a much more usable package. Unfortunately, it still doesn’t alleviate the many downsides to this swap.

The fact is these spindles were designed for a totally different car, and as a result you find a lot of issues. For example, the steering arms put the tie rod ends in the wrong location. The A-body starts out with massive bump steer (about 1.5 inches of total toe change over 6 inches of suspension travel) due mainly to a vertical misalignment of the outer tie rod ends. The B-body arms roughly double that misalignment and the resulting bump steer. The only factory cars I’ve ever analyzed that were worse than this were a few Chrysler products from the mid 1940s. This is just completely unacceptable in my book—you’re trying to make your car handle, steer, and stop better; not worse.

There’s more too; the steering arms are also about 1 inch longer. This slows down the final steering ratio, making the turning radius much larger. You can forget about doing U-turns in a reasonable arc, and the fast-ratio steering box you just spent good money on is now a not-so-fast ratio. The Ackerman error is also made worse, which makes for a lazier turn-in when cornering and more tire squeal when parking. This swap is often sold as part of a package with giant sway bars to inhibit individual wheel movement and reduce the amount of perceived bump steer, but that doesn’t fix the problem; it just masks it a little. In other words, if the steering does bad things when the suspension moves, then don’t let it move much.

But wait; that’s not all! The B-body spindles are also massively heavy when compared to the stock parts they replace. Their non-modular format is hard to adapt properly to modern brakes, and they increase the track width of the car by 3/8 inch, which can cause tire/fender clearance issues. They improve the suspension geometry markedly, but it’s at the cost of reduced performance everywhere else. This swap was a good first attempt, and at least proved that these cars could be made to handle. But the industry has made huge strides in the past 20 years and this concept’s time has come and gone.

Aftermarket Tall Spindles: Modern after-market tall spindles are designed to be a direct fit to the A-body platform and eliminate the pitfalls of the B-body spindle swap. For the most part, they do that pretty well. There are several varieties, and they’re not all created equally. First, they vary in height. Most are about 1.5 inches taller than stock, but some (like the Fat Man Fabrication spindle, for example) are about 1.75 inches taller. That may be a good thing on a car that isn’t lowered with springs, but it can be too much of a good thing on one that is.

Some of these tall spindles also feature relocated steering arm mount holes to improve (or at least change) bump steer. The Heidt’s product leaves them alone. This might be a good choice if you’re running a rack-and-pinion steering system that corrects the bump steer on the inboard side, such as the product offered by Unisteer. They are a “no harm—no foul” upgrade with stock steering.

Other manufacturers relocated the steering arms to a lower position for improved bump steer on 1967 to 1969 Camaro (first-generation F-body) applications. This is a good thing on a Camaro, but while they share the same stock spindles with 1965 to 1972 A-bodies (1964 is slightly different), they have a totally different steering design with opposite requirements for bump steer correction. That means that they roughly double the bump steer issue on an A-body. At least the steering arms are still stock length, so it avoids the steering-ratio and turning-radius issues of the B-body spindle swap. Even the outstanding American Touring Specialties (ATS) AFX tall forged-aluminum spindles have steering arm holes in this first-generation F-body optimized location. But ATS includes an A-body-specific set of aluminum steering arms, which I co-designed with them to correct the bump steer on the A-body platform.

Some other manufacturers have taken a much different engineering approach and have cunningly ignored the problem. As the saying goes, let the buyer beware! Check for yourself; take a gander at your stock spindle and notice where the steering arm mount holes are located (vertically, in relation to the bottom of the spindle). If you’re looking at A-body spindles where the steering arm holes are about 1/2 inch lower than stock, and they don’t come with new vertically offset steering arms, then you’ve got a serious bump steer issue. Keep looking elsewhere. The experts at Detroit Speed and Engineering (DSE) have bucked the “holes-in-the-wrong-place trend” and have relocated the holes upward on their A-body-specific spindles to achieve proper bump steer correction for the A-body platform.

A common theme with all of these aftermarket tall-spindle upgrades is that they have additional drop built into them. Most have 2 inches of drop when compared to stock. The ATS AFX aluminum spindles have 7/8 inch. This additional drop can be good or bad, depending on your total package. Two inches of drop teamed with an air suspension can let you run more air pressure (and therefore more spring rate) at a given ride height—a good thing. On cars running coil-over conversions, a 2-inch-drop spindle allows you to achieve lower ride heights with less lower A-arm bump travel. This gives a larger vertical envelope in which to stuff the coil-over shocks, so a longer coil-over and longer springs can be employed. Again, that’s generally a good thing.

Charlie Currie’s 1965 Chevelle combines classic lines with a high-tech, 770-hp, blown LS-series stroker motor, with a SC&C StreetComp-AFX front suspension, Currectrac trailing arms, Shockwaves, 14-inch-diameter 6-piston Baer brakes, and more. The result is a roomy, comfortable cruiser that handles like a slot car and has more horsepower than a Ferrari Enzo. (Photo Courtesy Currie Enterprises)

The infamous GM B-body spindle swap. In the mid 1990s, it was the only way to really improve the suspension geometry of 1964 to 1972 A-bodies. But, it trashes the steering geometry, steering ratio, and Ackerman. It adds weight, makes modern brake swaps much more difficult, and widens the track width, which can present wheel fitment issues. Enough people are removing these setups from their cars that some new tall spindles are made as direct B-body swap replacements, and old B-body swap components are getting hard to sell on online auctions. Better than nothing (maybe) in the 1990s, there’s a huge selection of better choices available today.

This is the stock 1965 to 1972 GM A-body spindle (1964 is the same, but has smaller 7/16-inch steering arm bolt holes). It’s compact, lightweight, modular, and allows easy mounting of modern brakes. But, it’s too short in relation to the rest of the suspension pickup points and its steering arm and mounting points produce unacceptable bump steer. (Photo Courtesy Chris Alston’s Chassisworks)

For contrast, this new DSE tall GM A-body spindle makes use of a much taller overall height, which raises the pickup point of the upper ball joint to yield proper negative camber gain. It also relocates the roll center at a higher point to reduce body roll. This spindle also incorporates a 2-inch drop to optimize its use with DSE’s front coil-over package. The steering arm mounting holes have been relocated farther upward to correct the majority of the factory bump steer. Although GM A- and early F-body cars shared the same factory spindle, they have different (and opposite) bump steer issues, so you can’t use the same fix for both cars. What makes the bump steer better on one makes it twice as bad on the other. Be careful: Some manufacturers sell the same spindle (with relocated steering arm holes) for both cars. (Photo Courtesy Detroit Speed and Engineering)

The exotic, and often elusive, AFX tall aluminum spindles were originally designed by Tyler Beauregard for first-gen GM F-bodies. When I did consulting with ATS to design the A-body package for these spindles, my solution was to design new aluminum A-body-specific steering arms to correct the bump steer issues. ATS did a beautiful job of sculpting those raw dimensions in 7075 T6.

Remember, whichever brand and type of tall spindle you choose, it must be part of an integrated system to work properly. Here’s a good example of how a tall spindle and A-arms are designed in CAD to work properly together. Using tall spindles with stock A-arms can make alignment and tuning a nightmare and in some cases is even dangerous. (Photo Courtesy Detroit Speed and Engineering)

An alternative to using tall spindles for geometry change is tall ball joints. Since the outboard pickup points for the suspension are in the ball joints themselves, it’s a very direct way to get the geometry gains you want. Although non-stock ball joints have been used for some racing applications for years, SC&C was the first to build whole, integrated suspension packages around the tall (modular) ball-joint concept and apply them to geometry-challenged muscle cars. Here, you can see that the upper ball-joint pickup point of a StreetComp Stage 2-Plus tall ball-joint package is nearly identical to that of a common-height GM A-body aftermarket tall spindle. Aftermarket spindles may have other built-in advantages (such as different brake mounting, larger wheel bearings, various amounts of drop, etc.), but the fundamental geometry can be changed just as efficiently either way. The tall-ball-joint approach is generally more cost effective.

Prior to the development of modular tall ball joints, race car builders often used adjustable-height mono-ball-style ball joints to fine-tune geometry. They work after a fashion but require frequent rebuilding, especially when used as lower ball joints. Another major limitation for street cars: They only have 16 degrees of travel in each direction (versus 32 degrees for conventional and modular ball joints). This effectively cuts wheel travel in half and can cause serious binding issues.

Prior to the development of modular tall ball joints, race car builders often used adjustable-height mono-ball-style ball joints to fine-tune geometry. They work after a fashion but require frequent rebuilding, especially when used as lower ball joints. Another major limitation for street cars: They only have 16 degrees of travel in each direction (versus 32 degrees for conventional and modular ball joints). This effectively cuts wheel travel in half and can cause serious binding issues.

Tubular A-arms, a tall drop spindle, coil-overs, and front sway bar, from Detroit Speed. The A-arms have greasable Delrin bushings and offset slugs for more caster adjustment. They play a very important supporting role in this package. (Photo Courtesy Detroit Speed and Engineering)

This A-arm-and-spindle package is from Chassisworks. Available in many configurations, this one has a double-adjustable coil-over and a standard-height drop spindle. It’s also available with tall spindles, single-adjustable coil-overs, or single/double-adjustable Shockwaves. (Photo Courtesy Chris Alston’s Chassisworks)

This SPC Performance A-arm package was custom powdercoated by owner Jamie Kimber. The upper arms adjust in the modern fashion with turnbuckles, doing away with shims. The lower arms feature modular spring pockets for adjustable ride height and have revised geometry designed to work with modern alignment specs, lowered ride heights, and modified suspension geometry. Combined with the right tall spindles or tall-ball-joint package, they are amazingly versatile. (Photo Courtesy Jamie Kimber)

The next evolutionary step was tubular arms with poly bushings. These arms were certainly more beefy and the bushings have less deflection, both of which are good. But, the rigid arms and hard bushings increase torsional binding even more. (Photo Courtesy Chris Alston’s Chassisworks)

In racing, it’s common to fabricate links and spacers to fit in place of the factory trailing arms. The Heim joints allow plenty of torsional freedom of movement, but offer no isolation from NVH. The race-level parts are also wide open to dirt and water and tend to wear quickly on street cars.(Photo Courtesy Chris Alston’s Chassisworks)

Another great choice is the Currie Enterprises Currectrac arms. They use a polygraphite race flex joint (called a Johnny Joint) on the frame end and a conventional polygraphite bushing on the axle end. While this configuration won’t flex as far as a double-flex joint arm in torsion, it flexes much farther than any car needs it to without binding. The thick bushings do an excellent job of isolating NVH, making them as smooth and quiet as stock arms but with much better performance. (Photo Courtesy Currie Enterprises)

A step up from base arms were the factory reinforced (boxed) arms. Note the plate welded to the bottom of the arm. This also fits up inside the channel to prevent factory sway bar mounting bolts from smashing the arms when they’re tightened. A side effect is how it prevents the normally-open U-channel from splaying and bending under heavy acceleration, which promotes wheel hop. Of course, this doesn’t help the rubber bushings. Boxing the arms increases torsional binding. Boxing the upper trailing arms is pointless; they’re under tension under hard acceleration and are even more hypersensitive to binding.

With conventional performance coil springs, 2-inch-drop spindles can start to cause some problems. Almost all the performance coil springs offered for these cars are also designed to lower the car’s ride height. Dropping the suspension some, with custom springs, does put the lower A-arms in a more favorable orientation for good geometry than stock. But adding 1 to 2 inches of spring drop to a car with 2-inch-drop spindles often leads to the headers and/or oil pan being introduced to the pavement. Since hitting the ground isn’t good for performance, that’s less than ideal. Only one manufacturer I know of (DSE) offers a set of performance-rate stock-height springs.

There are also some wheel and tire clearance issues with 2-inch-drop spindles. Since the spindle pin has been raised 2 inches, but the steering arms and tie rod ends haven’t moved, you’ve in effect moved them 2 inches closer to the inner lip of the wheels and the tire sidewalls. That may force you to run smaller wheels and tires than you otherwise could. Spindles that relocate the steering arms downward make this clearance issue even worse, and those that relocate them upward somewhat reduce it.

There’s also a more subtle effect of spindle drop on the A-body front end: a reduction in lateral roll center migration. Depending on how the geometry has been otherwise modified, this effect seems to peak right around 1 inch of drop; then it trails off again. That’s the reason for the 7/8 inch of drop engineered into the AFX spindles. Because most A-body performance lowering springs are 1 to 1.2 inches or so, you end up with about 2 inches of total front drop. This makes for a very nice, lowered (but still fully functional) ride height.

So, what about 2-inch-drop spindles that aren’t taller than stock? Do they move the critical pickup points to improve the geometry? No. Do they do anything to improve the steering geometry? No. Do they cause more wheel/tire clearance issues? Yes. Do they make it harder to use performance-bred lowering springs and still have a usable ride height? Yes. Well, three strikes and you’re out…and they got four. Make it five, because you already have stock spindles, and you have to pay for these 2-inch-drop spindles. Again, do the homework first, and know what you’re getting before laying out your hard-earned money.

Most tall spindles for GM A-bodies are the same general configuration as stock, in that they use the same iron construction and accept stock wheel hubs. The only one currently on the market that really bucks this trend is the American Touring Specialties (ATS) AFX tall forged-aluminum spindle. The first thing that catches your eye is that they’re made of forged 6061 T6 aluminum. Their overall look is much beefier than the stock spindles for strength, but the aluminum alloy keeps them light. The second thing you notice is that they have modern C5 Corvette hub/wheel bearing packs and late-model GM-style brake brackets forged right into the spindles. This combination delivers wheel bearings designed for serious cornering on modern tires and the ability to easily mount Corvette or any modern-format performance brakes to the spindles.

Generally, those brake packages are less costly than their stock spindle equivalents, which does help offset the higher cost of the spindles. When properly complemented with the right A-arms, springs, and alignment specifications, these spindles yield geometry rivaling modern performance cars and easily beat out many aftermarket chassis. If you have the budget, I highly recommend them. They also sparked interest in a market that I don’t think anyone but their designer (Tyler Beauregard) knew existed. Hopefully, in the near future you’ll see a lot more modern-format aluminum spindles like these hit the market. Some will probably go to billet construction and I’m sure at least one company will do a cheap overseas-made version. It’s almost inevitable that someone will make them, but you don’t have to buy them.

Aftermarket Tall Ball Joints: The other geometry correction method is based on using taller-than-stock ball joints. Circle track and road race teams have been using non-stock ball joints for years to make small changes in geometry, but since they were typically sourced from trucks, the mounting format is usually different than stock; often the tapers are different, too. This is not a big deal if you have a well-outfitted race shop, but the gains are still very modest. Some race cars use monoballs (spherical bearings) with ball-joint studs through them to tweak geometry, but they don’t hold up very well on the street (especially the lowers) and they only have half the angular travel of a factory ball joint. They only really work on cars set up race-car stiff.

Then, Howe Racing Enterprises designed the “Precision Series” modular CNC-machined ball joints. I remember seeing an ad for them in a magazine for the first time, and it hit me like a ton of bricks. I realized that I could fix flawed suspension geometry with these things and retain the stock spindles. I couldn’t wait to get my hands on some of these new components. The rest is history.

Since then, I’ve put together nearly a dozen tall ball-joint packages (sold as Savitske Classic & Custom StreetComp packages) for various cars. The most popular is for the GM A-body. The trick to working with these components is attention to detail. Because they’re modular, there are thousands of possible combinations and only one is ideal for a given vehicle and package.

Despite having so many options to choose from, I ended up working with Howe engineers to design several application-specific ball-joint components as well. All are CNC-machined, heat-treated steel with different coatings for each specific component. The resulting products are, in my opinion, the best of ball joints. They are super strong, super smooth, adjustable for wear/lash, and rebuildable. Since the outboard suspension pickup points are the ball joints, they’re a very efficient way to tweak the geometry.

Many aftermarket upper trailing arms are adjustable. If you’ve lowered your car or if you’d like to adjust the pinion angle for best traction or to reduce drive line vibration, then you need this feature. This Currectrac arm is “double-adjustable,” which simply means it has two locking nuts and can be adjusted without disassembling the arm. If you’ve ever taken the upper arms out or installed them, you know the double-adjustable setup is a luxury worth paying a little extra for.(Photo Courtesy Currie Enterprises)

These Chassisworks arms have TrueCenter Delrin race flex joints and are “single-adjustable,” which means they have a single locking nut and one mounting bolt must be removed to adjust them. This takes a little longer to adjust than the “double-adjustable” format, but once installed it can’t turn more than a few degrees even if the jam nut is loose, making it extra failsafe. (Photo Courtesy Chris Alston’s Chassisworks)

Greasable flex joints are a better all-around solution for street cars. The lower arm is a billet-aluminum unit with Delrin race TrueCenter pivots on each end. These have better NVH isolation than Heim joints and mono balls (metal spherical bearings in general). The closed construction, wider synthetic races, and grease all seal dirt and moisture out for a long, quiet service life. They flex through the same wide range of motion as a Heim joint to eliminate torsional binding. (Photo Courtesy Chris Alston’s Chassisworks)

Rear coil-over conversions for the GM A-body are becoming widely available. This one is from SpeedTech and incorporates several adjustment holes for the lower trailing arms as well. Note the swivel portion of the arms, which reduces torsional binding. This package also makes use of a link-mounted adjustable-rate rear sway bar. This makes for a well-rounded system with enough adjustment to dial it in for many different pursuits, from autocross to drag racing. Similar packages, each with their own twists, are available from DSE, SC&C, Hotchkiss, Global West, and Chassisworks. Take your time, check out the details of each system, and then make a well-informed decision on which one can work best for you.

When refinement of a system isn’t enough for you, there’s always augmentation. The use of Watts links with triangulated four-link suspensions is too new to be widely accepted, but from SCCA American Iron Extreme road racing to autocross and street use, its performance and drivability gains have to be experienced to be believed. Properly implemented, it takes all the skittish behavior out of the factory four-link and replaces it with smooth linear control. This one is being used in conjunction with an SC&C/Hellwig Performance adjustable-rate link-mounted rear sway bar. Its efficient design allows it to generate surprisingly high amounts of roll rate, which can be used to balance the suspension when the Watts is used to lower the rear roll center..

An interesting twist on front sway bars, the RideTech MuscleBar is similar to a splined end bar. It features Posi-Link end links and a massive tubular torsion bar.(Photo Courtesy RideTech)

The proper mounting format for a GM A-body is to get the bar off the trailing arms altogether, and run links mounted to the chassis. This example is an adjustable-rate tubular unit from Hellwig.

Don’t think that because I’m discussing a lot of trick suspension parts that we’re building race cars here. These parts are all about engineering efficiency and good tuning, and they pay off just as big on a super-clean cruiser like Richard Johnson’s Olds. With an SC&C Stage 2-Plus package up front, Currectrac trailing arms in the rear, and a Lee 670 fast-ratio steering box, it’s just the thing for a brisk cruise on a sunny day or to pick on the occasional BMW or Porsche. (Photo Courtesy Richard Johnson)

Technical improvements and performance are my focus, but even I admit there’s more than just technology to building a performance-handling muscle car. Looks are important too—no new car has this much street attitude. (Photo Courtesy SpeedTech)

Never lose sight of the big picture. This package includes a factory-format 1-inch rear bar. It’s not the best technical choice, but it is an economical one, which leaves more budget to spend on shocks, brakes, trailing arms, etc. You have to pick your battles, and it’s better to have a whole package that’s good, rather than one or two great parts and the rest still worn-out stock parts.

The Stage 2-Plus package rivals the geometry of a 2002 GM F-body, which is not bad for a simple bolt-on kit! This package uses the ball joints in non-stock heights to duplicate the improved geometry of a good, tall spindle with about 3/4 inch of drop. We also built in a roughly 80-percent-overall improvement in bump steer. I’m sure this idea will eventually catch on with other companies, but it’s gratifying to know we at Savitske Classic & Custom (SC&C) were the first to really run with it and perfect it.

By the way, don’t bother contacting Howe about using them for a street-based car. They do circle track race cars only. I mention them by name just to give them full credit for producing a great product.

Tubular A-Arms: All of the technical information I discussed in Chapter 4 also applies here. If you alter the geometry in a meaningful way, the stock upper A-arms need to go in favor of a set that was designed to complement the new geometry. The lowers can be retained if they’re in perfect shape with no cracks, dents, or rust, and if you’re only building a mild street-application car. Otherwise, I would rather see them replaced with some new tubular arms that are stronger, more rigid, and haven’t already gone through countless fatigue cycles.

There are lots of lower A-arms on the market for the GM A-body, so look them over closely before you buy. Most are tubular replacements for the stock arms, but stronger, and often with better bushings. There’s nothing wrong with them but I always felt that format could be improved upon.

Luckily, so did SPC Performance, and the result is a new lower A-arm with some very cool features. I admit I had a hand in designing these arms, so I may be biased, but the features are undeniable. The first is a modular lower spring pocket, allowing the use of conventional coil springs, coil-over shocks, or Shock-wave air springs. This modular pocket allows some extra room for the latter two for more bump travel. With conventional coils, the SPC spring shim kits allow you to change the ride height of the car without changing the springs.

The total adjustment range available is a massive 33⁄4 inches. That’s 2 inches of drop to 13⁄4 inches of lift. To change ride height, you just add or subtract spring shims with a 2:1 ratio. For instance, a 1/4-inch shim equals 1/2 inch of ride height change. There’s no guesswork. Greaseable Delrin bushings and provisions for modern progressive-rate jounce bumpers are also offered by SPC. Finally, they have modified geometry that re-centers the wheels within the wheel wells after you’ve added a bunch of positive caster. This feature can be a big help on lowered cars with big tires up front.

Springs and Shocks: Traditional coil springs, coil-over shock setups, or air springs—they can all work well, so it’s pretty much up to you. Conventional coil springs are the easiest to set up, the most durable, and by far the most foolproof.

In the A-body, coil-over shocks generally work better in the rear than in the front simply because there’s more room for a longer coil-over and room to swing the spanner wrench for ride height adjustment. It’s also harder to mess up the tuning (not impossible, just harder). Several companies offer bolt-in coil-over shock rear suspension conversions. It’s perfectly acceptable to run conventional performance coil springs and adjustable shocks in the front and the same brand of adjustable coil-overs in the rear. I often have clients do this with SPC Performance adjustable-height lower A-arms up front. That gives them a bulletproof system that’s easy to tune on both ends.

Four-Link Rear Suspension Issues: The A-body four-link rear suspension has some inherent binding issues, so try to minimize them with the correct-format control arms. With rear suspension arms, you want something with greaseable flex joints or at least a swivel in the middle of the arms to allow torsional freedom of movement. The roll center is very high, so run modest spring rates and tune with a rear sway bar. Note that as you lower the rear of a GM A-body, the rear roll center goes up. That’s one good reason not to lower the rear of an A-body any more than you have to. If you insist on lowering it more than an inch or so, consider one of two alternatives.

First, run large-diameter rear wheels and tall tires that fill out the wheelwells and give the car a lowered look, without being slammed. Second, add a frame-mounted Watts link, such as the one I co-designed with Fays2. The Watts link is something you may want to consider even if you haven’t lowered the car too much. The Watts link does an outstanding job of affixing the roll center, and since this is a frame-mounted Watts, it also couples it to the CG.

There’s also nothing better for lateral axle location. The Watts link makes the normally skittish, converging four-link factory suspension suddenly very linear, predictable, and precise. Remember to use rubber bushings in the axle “ears” to allow compliance in the upper trailing arms. This lets the Watts link do its job unhindered.

This package also allows you to lower the roll center a bit. Don’t get carried away, for best performance you want to keep the new roll center within the range it originally migrated in. Basically, this means don’t lower it more than 2 to 3 inches from stock. If you decide to lower it, expect to add more rear sway bar and or spring rate to keep the car balanced. If you run a Watts link, do you need to run a rear sway bar? Yes. They perform completely different functions and actually complement each other very well.

Sway Bars: The front sway bar choice varies with your desired level of performance and the overall package. Older designs tend to be one-size-fits-all, and can have fitment issues with larger tires and/or wheels with greater-than-stock backspacing. Some savvy companies have started building application-specific bars with better-than-stock clearance, such as the products offered by Hellwig, DSE, and RideTech. Tubular bars don’t work any better than solid units, but they’re a lot lighter. The racy splined-end bars don’t work any better than bent tubular bars or solid bars; they just look neater.

In the rear, conventionally mounted (to the lower trailing arms) bars are largely ineffective and cause binding in the arms. A 1-inch-diameter rear bar bolted to the lower control arms is better than nothing, but not by much. You want a link-mounted bar with links running all the way to the frame or crossmember. This is how bars are mounted on 99 percent of the cars in the world and it is the correct way to go about it.

Many of these have adjustable rates, which is great! It lets you tune the car to your combination and driving style. It’s best to always start out at the softest rate (the one farthest from the transverse torsion bar part of the bar) and tune from there.

GM A-Body 1973 to 1977

Owners of these cars have had it rough. Engine horsepower was down, and size and weight were up. The government-led, 5-mph battering-ram bumpers became mandatory and the A-body became more of a luxury cruiser than a muscle car. That is not to say that they didn’t build some cool cars, though—the Pontiac GTO and CanAm, Chevy’s Laguna S3, and the Hurst/Olds 442 were all great machines. What’s forgotten is how these cars actually had the best suspension of any of the A-bodies! Their front end and geometry was inherited from the 1970 to 1981 F-body, and those cars handled pretty well. They also have very respectable bump steer curves. The camber curves aren’t great, but they’re not backward either! The rear suspension is also slightly better, with longer trailing arms and less acute convergence angles.

These cars don’t need a tall spindle swap; they already have them. They can use a little help making the geometry more aggressive, and for that SC&C makes a Stage 1 package, with slightly taller upper ball joints. They can benefit from more rigid suspension arms and a good performance alignment as well. All the normal rules apply with regard to spring rates, shocks, and sway bars for tuning. These cars were set up very soft and plush from the factory, so a little tuning can really make a dramatic difference. The only thing really missing for these cars is a link-mounted rear sway bar, and by the time this book is in print, Hellwig should have an adjustable-rate tubular unit in production.

Note: The above information about the 1973 to 1977 A-bodies also applies to 1978 to 1996 B-body Impalas, Caprices, Roadmasters, and the like. They are all, for most intents and purposes, the same chassis. You wouldn’t think you could get much handling performance out of a car the size of a whale, but I have clients regularly challenging C5/C6 Corvettes and Vipers at autocross events and still driving them to work a couple of days a week. Amazing!

GM A-Body 1978 to 1980

Most people refer to these cars as G-bodies because this platform was renamed G-body in 1981. Any information that applies to G-body cars applies to these as well.

Few people realize that the GM B-body from 1978 to 1996 shared the same suspension with 1973 to 1977 A-bodies. It’s actually a good-performance platform, in spite of its size and weight. Tad Banzuelo’s 4,200-pound 1995 Impala SS has garnered him a pile of autocross trophies running against late-model Corvettes, BMWs, and the like. A cool 1973 to 1977 A-body (like a Laguna S-3 or 1977 Pontiac CanAm) should do just as well. (Photo Courtesy Tad Banzuelo)

Like GM A-body cars, G-bodies are often thought of as just drag cars. This is especially true of the Buick Grand National turbo V-6 cars. This is funny because they can be some of the best handling of all the G-bodies. (Photo Courtesy W. Wilkerson)

The last of the GM A-bodies (1978 to 1980) were thereafter called G-bodies. This slightly downsized platform shares the same components as 1981 to 1988 G-body cars, so there is a great selection of parts available for them. Tony Reiss’s Monte Carlo shows they can be really cool street machines too. (Photo Courtesy Tony Reiss)

GM G-Body 1981 to 1988

I was going to give these cars a section of their own, but they really don’t need it. All of the information pertaining to the 1964 to 1972 A-bodies can be applied to the G-body platform, with one exception. At the time I’m writing this, there is only one aftermarket tall spindle option: the American Touring Specialties (ATS) AFX aluminum spindles. Thank-fully, it is a great option. We did even more work on this one and incorporated some steering geometry tweaks from the older C5 Corvette spindle conversion package. That setup was very effective, but also expensive to build and was limited to pretty low ride heights.

The SC-AFX package is less expensive and more versatile. The steering modifications fix the factory steering Ackerman issues and also slightly quicken the steering ratio. The response and turn-in are incredible. The G-body platform is typically lighter than the older A-body cars and much lighter than modern cars in the same class, so performance can be fantastic.

One inherent G-body problem is that it’s not a very rigid platform. GM put them on a diet and started by removing the forward and aft chassis crossmembers. They also cut away most of the cowl structure, the steel dash structure, and much of the rear seat bracing to save weight. Some models had various conduit-like tubular braces here and there, which were better than nothing, but still far from ideal. The T-top cars are especially flexible because they lack some of the torsional rigidity of a full roof. For this reason, I designed the SC&C HD Chassis brace for G-bodies. It ties the front frame rails together and adds triangulation to the front end.

The performance-handling potential of the G-body is obvious in John Follweiler’s wicked turbo T-Type. (Photo Courtesy John Follweiler)

Early on, the ill-conceived B-body spindle swap was the only option for G-body owners looking for better handling. Then, SC&C released the G-5 package in 2003. Based on modified C5 spindles with unique steering arms and Pole Position Racing (now SPC Performance) adjustable upper A-arms, it was a quantum leap forward. Newer systems have come along since, but the G-5 showed what was really possible with this platform. (Photo Courtesy John Follweiler)

The StreetComp-AFX package came a few years later, based on the excellent AFX tall aluminum spindles. It required some re-engineering, but the spindle’s modular format made it possible to build a G-body-specific package that was much less expensive than the G-5 package. (Photo Courtesy John Follweiler)

Another very popular option with first gens is to simple swap out the old subframe for a brand new one with the features you want built into it. This subframe is from SpeedTech and it’s unique in that it accepts many of the same parts that fit stock subframes. It does away with the stock steering box in favor of a rack and pinion, which also frees up some wheel and tire room. It also has a built in G Mod or it can be ordered with AFX tall aluminum spindles. (Photo Courtesy SpeedTech Performance USA)

The gStreet subframe from Chassisworks takes a different approach and uses a totally clean sheet design. With four A-arm options, two sway bar options, five coil-over or air spring options, six steering rack options (they’re even available in right-hand drive!), four transmission crossmembers, etc., etc., it can be dialed in for anything from a big-block drag car to an LS-powered road race car or a chromed-up show car. (Photo Courtesy Chris Alston’s Chassisworks)

The Detroit Speed subframe takes yet another approach, incorporating C6 Corvette spindles and their own unique rack and pinion, splined end sway bar and coil overs. This clean, modern design is an obvious complement to their Quadralink rear suspension package. (Photo Courtesy Detroit Speed and Engineering)

This Camaro, owned by Dan Babb, is pretty typical of a traditional muscle/pony car. Armed with 427 inches of big-block power, it has virtually stock suspension with slapper bars in the rear. It features massive body roll even at modest autocross speeds. Training wheels on the door handles might not be a bad idea! (Photo Courtesy Dan Babb)

Here’s the same car a few months later. The slapper bars are gone, and an SC&C Stage 1-Plus front suspension and Hellwig tubular front and adjustable-rate rear sway bar have been added. Seen here at Sebring’s road race track at high speed, body roll is hardly discernable. The blue tape is to protect the paint from stone chips and to keep the windshield trim on at very high speeds. Dan experienced an obvious night-and-day improvement in handling with a few well-chosen bolt-on parts. (Photo Courtesy Dan Babb)

To give you some idea of how flexible these cars are, the brace only fits if it’s installed with the weight of the car sitting on its wheels. Boxing the center span of the frame rails and/or adding firmer body bushings is also a good idea. Be sure to at least replace the radiator support bushings; they’re especially soft and allow far too much movement. Bracing up the chassis also keeps your body panel gaps consistent.

The limited-production Buick GNX torque arm/Panhard bar setup is not a particularly well-designed suspension and should be avoided. The torque arm is too short and in a compromised location due to packaging limits. The Panhard bar is too short and not level at factory ride height. You are better off tweaking the factory converging four-link. It’s a shame the GM engineers didn’t spend the same time and effort on overhauling the front suspension instead.

GM First-Generation F-Body

These are arguably the cars that started the “performance handling for muscle cars craze.” The 1967 to 1969 Chevy Camaro and Pontiac Firebird are undeniable classics and make great performance platforms, once you change the suspension all around so it works properly. First-generation cars suffer from the same abysmal suspension geometry as the early A-bodies and have similarly poor bump steer curves as well. The solutions to these issues are where they differ some.

Tall Spindles and Ball Joints

There is a plethora of tall spindle options for the first gens; in fact most of the A-body tall spindle modifications started here. In this case, the steering arm mounting holes issue is less of a concern. Those with relocated steering arm mount holes were almost all designed with the first gens in mind, so you’re generally good to go. The cautions about wheel/tie rod end clearance issues with 2-inch-drop spindles apply even more to this platform. The steering arms are bent down much closer to the wheel/tie rod ends than on the A-body to begin with, and the bump steer solution moves the tie rod ends down even farther still. If you run a 2-inch-dropped tall spindle on these cars, measure very carefully for your wheels before you buy them. Similarly, if you already have the wheels you want to run, measure very carefully to see if you’ll still have enough clearance when you lose 2 inches of it.

Cars with bolt-in subframes can benefit from down bars running from the top of the cowl structure (or an interior roll cage) to the ends of the subframe. With these in place, the subframe is no longer cantilevered out in front of the unibody. These beefy down bars were fabricated by DSE. Bolt-in down bars for stock subframes are available from Chassisworks, and many aftermarket subframes come with them or have them as an option. (Photo Courtesy Detroit Speed and Engineering)

An interior shot of Camaro weld-in subframe connectors prior to welding. The floor has been notched to give more ground clearance and tie the connectors into the body structure for more overall rigidity. Solid aluminum subframe bushings are also recommended. (Photo Courtesy Detroit Speed and Engineering)

The subframes are usually mounted to the unibody structure with rubber bushings. Note the one mounting the radiator support. These bushings are supposed to isolate NVH. They don’t do a very good job because they typically deflect under loading, allowing the whole subframe to move in relation to the rest of the car. (Photo Courtesy Chris Alston’s Chassisworks)

Others, like this Nova, are unibody, using complex folded and welded sheetmetal structures for the majority of the body structure with a separate subframe to mount the front suspension, engine, and transmission. You can see the back end of the subframe rails in the highlighted red boxes. (Photo Courtesy RideTech)

Detroit Speed’s Quadralink has made a name for itself in autocross exhibitions around the country. It requires some cutting and welding, and changing of all the axle brackets to install, but this also makes for a very factory-looking finished installation. The parallel four-bar format, combined with a long and level Panhard bar, has very benign handling characteristics. Swivel-link trailing arms and the overall geometry combine to make torsional binding almost non-existent. (Photo Courtesy Detroit Speed and Engineering)

A tall-ball-joint package is also available from SC&C for the first-gen F-bodies, but it differs from the A-body package in that it retains the stock lower ball joints and instead includes tall tie rod ends for bump steer correction.

Guldstrand Mod

There’s still another option for first gens that doesn’t exist for other GM cars called the Guldstrand mod. Named after legendary racer Dick Guldstrand, who pioneered it, this modification relocates the cross shafts of the upper control arms down and toward the firewall to move the inner pickup points for improved geometry and for more positive caster. This was first done in the SCCA Trans Am racing series to basically cheat. They would cut the factory welds securing the upper A-arm mounting brackets to the subframe, section them, and then re-weld them back on, closer to the firewall. Done correctly, it was very hard to tell they had been tampered with. In the modern version (with no SCCA tech officials to scrutinize) folks simply re-drill the cross shaft mounting holes. There were many different versions of this modification back in the 1970s, and there are still more today. Everybody seems to have their own version, even me.

Rather than mixing metaphors, Brad Granger chose versatile components from the outset when building his killer 1967 Camaro. A Magnacharged LSX motor makes huge power while being completely streetable and docile. Also the Chassisworks G-Machine front subframe and G-Bar four-link/coil-over rear suspensions are both multi-purpose. With a few shock and sway bar setting changes and a set of R-compound radials, it can carve corners or pull killer holeshots with the best of them. (Photo Courtesy Brad Granger)

The Chassisworks G-Link is also a triangulated four-link arrangement. This one is shown bolted to an original GM 12-bolt rear axle. Installation is nearly as simple as the AirBar, using several factory holes to locate the mounting cradle, but the G-Link should also be welded in place. Weld-on axle mounts are available to those who want them. This makes the unit rock solid and allows the cradle to impart additional strength to the factory unibody structure, which is a big plus on high-horsepower cars. This package has numerous options, such as the sliding link adjustable-rate sway bar (shown) and billet-aluminum arms (also shown). It can be ordered with non-adjustable, single-adjustable, or double-adjustable coil-overs or the same choices in a Shockwave. It can be ordered for standard or minitubbed applications as well.(Photo Courtesy Chris Alston’s Chassisworks)

Mini tubbing is a great way to make your first-gen F-body stand out from the crowd. With the proper underpinnings it can yield great performance, too. Today almost everyone offers this as an option, but DSE was the first to offer a comprehensive kit. (Photo Courtesy Detroit Speed and Engineering)

So, is this the answer to all your hopes and dreams—a cheap fix that turns your car into a road racing machine? Well, not really. It is a step in the right direction, but it has issues too. When you re-drill the holes, the top of the perch hits the inside of the factory A-arms and has to be modified for clearance without weakening it too much. The more you lower the cross shafts, the closer they get to the subframe, and the less droop travel you have. Since droop travel can improve ride quality without adversely affecting handling, that’s a bummer. The post-mod geometry is better than stock, but still not great by any modern yardstick. Finally, it makes it even more challenging to get a good performance alignment. The relocated perches worked better in this regard, but not everyone wants to cut up their classic car. Once you cut stuff off, it’s hard to put it back again.

Subframe Options

Because these cars have removable front subframes, they also have another option. It’s possible to swap out the whole thing for an aftermarket one. They range from the SpeedTech unit that uses almost all stock-configuration aftermarket components (except for rack-and-pinion steering) to designs from Art Morrison and DSE that make use of C6 Corvette spindles and some other upgraded components.

Generally, these subframes use either coil-over or Shockwave air springs and they’re usually easier to work with on these dedicated subframes than they are when used as a conversion on a factory subframe. All the aftermarket subframes I’m aware of use rack-and-pinion steering. That’s usually viewed as a good thing. They also typically allow for somewhat wider front tires, because some extra clearance was freed up by using the rack-and-pinion and moving the sub-frame rails inboard. The extra clearance could also have been gained because the rack-and-pinion used in the package has a larger turning radius and, therefore, more clearance because the wheels don’t turn as far. Watch out for that one!

The Chassisworks G-Street subframe has a wide array of options from mild to wild. Everything from the hardware to the sway bars and A-arms can be upgraded. It’s a competent performer in any of its guises and can be configured to do anything you want, from shiny show car to road racing.

Rear Suspension Options

The rear suspension of the first gen is another area that can use some improvement. The old parallel-leaf-spring Hotchkis-drive format has some issues, as I discussed earlier, but it can still be made to function very well. A good set of performance leaf springs, an adjustable rear sway bar, and a Watts link can take the old parallel-leaf-spring design to a whole new level of handling.(See the sections on leaf-spring tuning and augmentation in Chapter 2 for more details.)

The other option is to upgrade to one of the many aftermarket link-type rear suspension systems available. These range from direct bolt-in kits (like Chassisworks’ G-Bar) to more involved weld-in systems that require modifications to the floor and/or unibody (like DSE’s Quadra-link). Most of these systems are four-link designs, but there are some exceptions here as well. The Lateral Dynamics–sourced three-link/Watts link and SpeedTech’s torque-arm system are good examples.

Each of these designs has its strengths and weaknesses. Some have very little adjustment and may be best for those who aren’t well versed in how the suspension works. Those will, how-ever, be more limited in how many things they can do well. I am a big fan of the more-adjustable systems with adapt-able geometry, because no two cars and clients are exactly alike.

I’d rather spend time consulting and dial the car in exactly to the client’s needs than to accept the tradeoffs of a one-size- fits-all package. The higher the power level of the car, the more adjustability comes into play. A 400-hp car hooks up with just about any suspension, as long as it has decent tires. A 650-hp car is a whole different story, and requires a suspension with enough anti-squat to help plant the tires. It also requires very beefy components and low-deflection pivot points to maintain good control.

In general, and this is by no means an all-inclusive list, systems like the Chassisworks G-Bar, SpeedTech Torque Arm, and DSE Quadralink are excellent choices for a high-performance street car, with crisp handling and great ride characteristics. They would also be great choices for casual autocross use. They work best in a narrow range of ride heights and don’t have a lot of geometry adjustment. So if you’re planning on doing a lot of drag racing or running the car with a higher or lower stance than the manufacturer recommends, they may not be ideal choices.

Here is a first look at Chassisworks new torque- arm system for first-generation F-bodies. It’s built around a sophisticated Watts linkage with adjustable roll-center height. The trailing arms feature Delrin race greaseable spherical pivots at both ends for smooth articulation. Note the variety of geometry and tuning positions available that allow for different ride heights and uses. (Illustration Courtesy Chris Alston’s Chassisworks)

Second-gen GM F-bodies like Brett Anderson’s Camaro are becoming more and more popular. This car features a late-model LSX engine and 6-speed transmission with custom StreetComp-AFX front suspension. The rear suspension consists of a Chassisworks G-Bar with SC&C billet-aluminum arms. Brett built the whole car himself in a two-car garage, including the paint and bodywork. It goes to show how you don’t have to spend a fortune at a big shop to build a world-class modern hot rod. (Photo Courtesy Brett Anderson)

Taking a different approach altogether is SpeedTech’s torque arm system. Similar in format to the rear suspension of 1982 to 1992 and 1993 to 2001 GM F-bodies, this seems a natural retrofit to earlier F-bodies. Torque arm suspensions are known for exceptional cornering performance, mild roll steer, and neutral behavior. This package has optional mounting positions for the lower trailing arms to allow some anti-squat and IC adjustment, which factory torque arm suspensions lack. Installation is simple and straightforward. It requires cutting and welding on the axle tubes, but not the unibody. (Photo Courtesy SpeedTech Performance USA)

Here’s a more traditional approach, with old-school American Racing Torque Thrust wheels, a 454-inch big-block, and Hugger Orange paint. With a few sensible modifications like springs, shocks, and sway bars, this style of car can also be a capable performer. Believe it or not, this is the same car seen on page 117 before its latest modifications. (Photo Courtesy Brett Anderson)

At the extreme end of the spectrum is Steve Johnston’s supercharged, open-course road race car. It packs a 1,600-hp, stroker big-block V-8 and is to be fully street licensed. With that much power, the suspension has to be up to the task. It runs a custom four-link with a Panhard bar in the rear, and a custom SC&C StreetComp-AFX package in front. Aerodynamics also become very important at high speeds, where air starts to react more like water, so it must incorporate many aero upgrades as well. This car should be able to achieve rear wheel spin at 150 mph—oh baby! At this level, cars aren’t just toys; they’re as serious as a heart attack. (Photo Courtesy Steve Johnston)

For putting big power down, the adjustability of the Chassisworks G-Link system is hard to beat. It has enough adjustment built into the system that it can be optimized for everything from street performance to autocross and road race duties to drag racing without replacing any parts. Other high-end systems may surpass the G-Link slightly in one department or another, but the G-Link is the best multitask design I’ve seen. It uses really beefy components and bulletproof Delrin race, greaseable pivot balls at all eight suspension pickup points. It can be configured to work well at a variety of ride heights. This system offers two choices for rear sway bars: an axle-mounted tubular bar or a frame-mounted adjustable-rate solid bar. Note that some of the other systems do not have a sway bar available, which limits tuning options.

Both the front subframe and link rear suspension conversion markets are flooded with offerings, and I’ve missed a lot of them here. Some that I’ve not mentioned are admittedly good ones, but using the technology from earlier in the book and studying the few examples I’ve referenced here should help you apply that knowledge to any other system you see. This certainly can help determine if it’s going to work well for you and your car.

Almost all of these rear systems are designed to work in mini-tubbed applications as well as in cars with stock wheel wells. Some offer a mini-tub-specific version, so be sure to order the right one for your application.

Should you mini-tub your car? Bigger tires generally equate to more traction, with all else being equal. Improved traction means putting more power to the road, which is the goal here. At the end of the day, it’s probably as much about getting the right look as anything else, but this is a cosmetic option that also adds performance. If it’s in the budget and you like the look of a mini-tubbed car, go for it. If not, spend more time researching good tires, especially R-compound tires, and you can still get awesome performance out of your car.

Whatever suspension package you decide on, don’t forget you need a rigid chassis to let all of those cool parts do their job efficiently. Subframe connectors are a must-have, and harder-than-stock or even solid body-mount bushings are a good idea as well.

GM Second-Generation F-Body

It’s good to see second-generation (1970 to 1981) GM F-bodies starting to soar in popularity. I’ve always thought they were great-looking cars and they’re a really good performance-handling platform. The front suspension, designed by Herb Adams, is competent even by modern standards. The advantage of running a geometry improvement package (such as an SC&C Stage 1 setup) is that its dynamic geometry allows you to get the same handling with street alignment specs where you’d normally have to run race alignment specs. In doing so, you can have great handling, good tire wear, and excellent street manners too.

An intermediate option is a Speedtech Street Fighter package, featuring AFX 2.0 spindles, tubular A-arms, a weld-in long-travel coil-over conversion, and revised steering. It splits the difference between mild bolt-ons and a full aftermarket subframe.

The final level is an aftermarket sub-frame offered by Chassisworks, DSE, and many others manufacturers. These run the gamut from excellent to no better than stock so do your homework before you buy!

Detroit Speed has a good selection of parts for second-gen GM F-bodies, including tubular A-arms, Quadralink rear suspension, and mini tubs. This DSE test car has had some outstanding autocross performances. (Photo Courtesy Detroit Speed and Engineering)

The rear leaf-spring suspension responds to all the same modifications and aftermarket link-type rear suspension packages as the first-generation F-body, so I won’t rehash it all here. The selection of packages isn’t as large for the second-generation cars, but most of the best players are well represented.

The biggest design flaw with the second gen is chassis rigidity, and it seems particularly noticeable on the later, heavier second gens. If your car doesn’t have subframe connectors in it, don’t even think about building the car without them. Again, harder-than-stock or solid subframe bushings are a very good thing to consider as well. There are also some underhood structure kits, pioneered by Herb Adams/VSE. These are another great idea. If you own a second-gen F-body and you’re disappointed that this section is as short as it is, don’t be. It means you chose a good performance-handling platform to start with.

GM Third-Generation F-Body

Honestly, I wasn’t going to include these cars in the book. The performance versions (such as the IROC Camaros and WS6 Trans Ams) are already very competent handling cars, even by modern standards. Also, to me, these aren’t old muscle cars. Of course anything with a third brake light is a newer car to me.

Third-generation GM F-bodies are great-handling cars out of the box. This ultra-clean original IROC, owned by Scott Moyer, out-handles a 2010 Z28 as is. There’s always room for improvement, though, and with new subframe connectors and performance trailing arms, they can do even better! (Photo Courtesy Scott Moyer)

Chassis Rigidity

Chassis rigidity is still a big issue with these cars, and as always the T-top cars are worse than the hardtops. There’s no need for different subframe bushings here, since these cars don’t have any. But subframe connectors are still very important. Because they have strut-type front ends, they also pass dampening loads (they still use conventional springs) into the strut towers, so a strut tower brace is a good idea. If you can use it as part of a bolster to triangulate the front end structure, it’s even better. There is also a brace available to tie the two sides of the front subframe together for better steering response. The IROC- and WS6-optioned cars came equipped with these, but the aftermarket-sourced ones are generally more rigid. These prevent the subframe from cracking at the steering box mounting point, which is sometimes an issue with these cars. There are even gussets available to brace the lower A-arm mounting section of the K-member (sub-frame) to the unibody for more rigidity.

An important point with torque arms is how the front mount must allow the bar to move fore/aft to avoid conflict with the lower trailing arms. This one uses a shackle, and goes one step further with a spherical joint to prevent torsional binding. (Photo Courtesy Spohn Performance)

The rear suspension consists of a torque arm, lower trailing arms, and Panhard bar. All are rather flimsy in stock form and should be upgraded for serious performance use. (Photo Courtesy Spohn Performance)

The Panhard bar originally used on these cars is way too flexible. It should be replaced with a more rigid tubular unit with less-compliant bushings. This one incorporates adjustable-length capability to center the axle at different ride heights, a low-deflection greaseable poly bushing on one end, and a greaseable Delrin race Delsphere flex joint on the other. This is a great combination of strength and NVH absorption. (Photo Courtesy Spohn Performance)

Component Options

Geometry isn’t really a problem with these cars but flimsy suspension components are. One look at the factory Panhard bar leaves you shaking your head. It’s a thin U-channel with very soft bushings on both ends. This is not the best thing to laterally locate the rear axle under heavy cornering loads. Upgrading to a more rigid tubular bar with low-compliance bushings is a great idea. If you intend to lower the car’s stance, an adjustable Panhard bar lets you re-center the rear axle under the car.

One area where there is room to improve the design is to substitute a Watts link for the Panhard bar. A frame-mounted Watts link setup adds a new crossmember and more chassis rigidity as well as improving dynamic handling. The lower trailing arms are also flimsy; in fact they’re basically the same arms used on the G-body. All of the previous tech information on trailing arms applies here, too.

Because this is a torque arm suspension, you don’t have to be concerned with upper trailing arms, but the torque arm can be a matter for concern. If you’re trying to harness a bunch of horsepower, you’ll want to upgrade the factory part to prevent deflection under heavy acceleration. Be cautious of the front-mounted bushing design. It needs to be free to move fore/aft without binding as well as being able to move freely in torsion. Normally, these bolt to the transmission tail-shaft and transfer a lot of stress to the transmission mount, so if you want to plant some serious power, consider one that relocates this mount to the sturdier crossmember.

A better, albeit more expensive, option is to replace the whole Panhard bar with a frame-mounted Watts link. This is a bolt-on system from Fays2. A Watts link provides even more positive axle location and a more stable roll center location. Apparently, all third-gen F-body parts are bright red. (Photo Courtesy Fays2)

Third gens are fairly easy to convert to a coil-over format. This is a Spohn package, which allows for adjustable ride height. It’s unique because it fits to any existing strut (except Bilstein), in this case a Koni Red. (Photo Courtesy Spohn Performance)

Third-generation GM F-bodies have a somewhat unusual front suspension, using a combination of conventional springs along with MacPherson struts. This one is fitted with Spohn Performance tubular lower A-arms and Bilstein struts. (Photo Courtesy Spohn Performance)

The third-generation F-body subframes are much smaller than those used in first- and second-generation cars. They can still be replaced to save weight and improve chassis rigidity, or to accommodate a different engine (like a big-block or LSX). Another upside: They’re much less expensive than those for the earlier F-bodies. This is a Spohn unit and, of course, it’s red. (Photo Courtesy Spohn Performance)

Aftermarket torque arms are generally adjustable for optimized pinion angle, which is a plus. Torque arms are generally not known for having great anti-squat, but you can improve this (usually at the expense of increased roll steer) with weld-on lower-trailing-arm relocation mounts. These drop the rear of the trailing arms to increase anti-squat and traction.

The third gens don’t have a subframe per se; they have more of a Mopar-style K-member. There are no geometry gains to be had by changing to a tubular one, but you can pick up some extra chassis rigidity while losing a little weight. They can be had configured for big-blocks and LSX motors if you’re doing an engine swap. Because they’re not full subframes, aftermarket K-members cost a fraction of what the full subframes for earlier Camaros or Firebirds command.

Written by Mark Savitske and Posted with Permission of CarTechBooks

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